固相法和共沉淀法制备La_(2/3)Sr_(1/3)MnO_3:Ag_x多晶材料性能比较  

Properties of La_(2/3)Sr_(1/3)MnO_3:Agx Polycrystalline Material Prepared by Solid State Reaction and Chemical Coprecipitation Methods

作　　者：晏益志[1] 刘翔[1] 陈清明[1] 

机构地区：[1]昆明理工大学材料科学与工程学院,云南昆明650093

出　　处：《热加工工艺》2013年第6期1-4,共4页Hot Working Technology

基　　金：国家自然科学基金资助项目(50974066);云南省自然科学基金资助项目(2009ZC013M)

摘　　要：分别采用固相法和共沉淀法工艺制备了不同Ag掺杂量的La2/3Sr1/3MnO3∶Agx(LSMO∶Agx,x为摩尔百分比,x=0.00、0.10、0.20、0.30、0.40)多晶材料,通过XRD和R-T对La2/3Sr1/3MnO3∶Agx材料的结构和性能进行测试分析。XRD分析结果表明,系列样品为正交菱面体结构,没有出现Ag元素的峰,这与Ag在高温烧结时的挥发有关;随着组分x的增加,固相法系列样品晶胞体积呈无规律膨胀,而共沉淀系列样品晶胞体积呈增大趋势,这可能是由于固相法系列样品的粒径较大且不均匀,导致LSMO∶Agx晶格有较多的缺陷使晶胞体积发生膨胀,而共沉淀系列样品的粒径较小且均匀,Ag+进入晶格替代Ag位的La3+或Sr2+,引起晶胞体积发生微小膨胀。R-T分析结果表明,相对于同一组分x,共沉淀比固相法系列样品有更低的电阻率及更高的TCR值,Ag掺杂能有效改善LSMO材料的电阻率及TCR;共沉淀系列样品Ag掺杂对LSMO材料电阻率及TCR调制作用更明显。La2/3Sr1/3MnO3：Agx（LSMO：Ag,x is mole percentage, x=0.00, 0.10, 0.20, 0.30, 0.40） polycrystalline materials were prepared by solid state reaction and chemical coprecipitation methods. The structure and performance of La2/3Sr1/3MnO3：Agx materials were investigated by XRD and R-T. The XRD analysis results show that the samples are rhombohedral crystal structures and diffraction peaks of Ag have not appeared, which is related to the volatilization of Ag in the high-temperature sintering. With the increase of x component, the crystal cell volume of the samples prepared by solid state reaction are expanded while the crystal cell volume of the samples prepared by coprecipitation increases. The lattice defects of LSMO： Agx prepared by solid state reaction are produced due to large particle size and worse uniformity. However, the samples of LSMO： Ag, prepared by chemical coprecipitation are fine and uniform. The crystal cell volume of LSMO： Ag, prepared by chemical coprecipitation increases when Ag＋ occupied the site of La3＋ or Sr2＋. R-T results show that the samples ofLSMO： Agx prepared by chemical copreeipitation have lower resistivity and higher TCR value than the samples prepared by solid state reaction with the same x component. Ag addition can improve the resistivity and TCR of LSMO materials effectively. The modulation of Ag addition to the resistivity and TCR of LSMO： Agx samples prepared by chemical coprecipitation is more distinct.

关 键 词：LA2 3Sr1 3MnO3 Agx(LSMO Agx) 固相法 共沉淀法 电阻温度系数(TCR) 

分 类 号：TG113.2[金属学及工艺—物理冶金]